ES2222046T3 - COATING COMPOSITION. - Google Patents

Abstract

A pigmented solventborne paint pack which can be made into a waterborne coating composition is provided, which comprises: i) a solution in an organic solvent of polymer having functional groups and hydrophilic groups; and ii) a waterborne pigment dispersion comprising pigment dispersed in water in the presence of a pigment dispersant, the aqueous pigment dispersion itself being in dispersion in the solution of i). Also provided is a solventborne activated paint pack comprising the paint pack described above and further comprising a crosslinker which is dissolved in the organic solvent. Further provided is a waterborne coating composition which comprises a dispersion in an aqueous medium of the solventborne activated paint pack.

Description

Coating composition.

This invention relates to a composition of coating, to certain intermediate compositions in their preparation, a process to prepare the composition and the use of the composition in a coating process.

A significant market for paintings is the repainting of motor vehicles after repair or reconditioning for collision damage. This is frequently makes reference as automotive refinishing. One of the most common types of automotive refinishing paints currently in the market comprises a polymer with hydroxyl function and a polyisocyanate crosslinker in an organic solvent. Because that the polymer and the crosslinker react together from the moment in which they are mixed, they are normally distributed to the end user as two independent components that mix shortly before use them For this reason, they are often called "two paintings" components. "

In practice, the component that contains the polymer also contains other components such as pigments, fillers, diluents or other additives that may be necessary to give the Paint your final color or to modify its properties. The pigments or diluents are particulate materials that remain in stable dispersion in the solvent-based composition by a pigment dispersant. When preparing the compositions, first of all a base pigment mixture is usually made with pigments, fillers and diluents. A base mixture of pigments mixing pigments, fillers and diluents and the pigment dispersant, usually with a little solvent, in a high shear mixer like a ball mill for Thoroughly separate the pigment particles and coat them with dispersant The resulting base mixture is then combined with polymer and solvent to form the composition known as "paint mix" sold to the end user. The user then combine this paint mixture with a solution of crosslinker in organic solvent, referred to as "hardener", just before using it.

There is an environmental and legislative pressure to reduce the emission of organic solvents from coating compositions when they are applied and dried to Form a coat of paint. One way to achieve such reduction It is to use water-based compositions.

Produce a water-based equivalent of the two-component paint for automotive refinishing described previously it is not simply a matter of replacing all the water solvent. Each component must be modified to do so soluble or dispersible in water. Particularly the modification would necessarily involve the introduction of hydrophilic groups in the crosslinker that must be made dispersible in water. It has been discovered that the introduction of hydrophilic groups in the crosslinker makes the final coat of paint more sensitive to water, making this route not attractive to produce high performance refinishing paints with good resistance to Water.

In an alternative (see document EP-358979) the polymer is produced in a solvent organic. Upon completion of the polymerization reaction, the organic solvent and the polymer becomes a solution or aqueous dispersion Then you can add the pigment to the aqueous solution or dispersion of polymer (if necessary), before of adding isocyanate crosslinkers.

However, it is desirable to obtain coatings with improved water resistance compared to the water resistance of coatings produced in accordance with the EP-358979. This is achieved according to the present invention using a solution in an organic solvent of polymer with functional group and hydrophilic group in which it has dispersed a dispersion of water-based pigment.

An alternative method proposed to produce a Two-component water-based composition uses a mixture of solvent based paint. The polymer and the crosslinker are they choose to be soluble in an organic solvent and it is made the pigment base mixture using a pigment dispersant solvent compatible. The polymer dissolves and the pigment it is dispersed in the organic solvent to form the mixture of solvent based paint. The end user dissolves the crosslinker in the solvent-based paint mixture to form a mixture of activated paint that is then dispersed in water to form the water-based coating composition ready for use.

It has been discovered that this route can provide two component water-based compositions with a yield equivalent to that of compositions based on solvent The problem with this route is that although the most of the transport fluid can be water, there is a relatively high level of solvent present in the mixture of solvent based paint. The solvent levels in essentially water-based compositions are often expressed as volatile organic content (VOC) in grams per liter of composition not including water (g / l). In the case of compositions of primer, these types of composition still have a VOC in the 350 g / l region. This is a lower level than the compositions of conventional solvent-based primer, although current and future regulations are directed towards a level of 250 g / l, and it is clearly desirable to have an even lower level. At case of single layer final finishing compositions these types of compositions still have a VOC in the region of 420 g / l, which of again is lower than that of the finishing compositions Conventional solvent-based final, although normative Current and future are directed towards a level of 340 g / l, although it is Clearly desirable an even lower level.

The authors of the invention have now discovered that it is possible to reduce the VOC of these types of compositions, using a base mixture of water based pigments. This base mix water-based disperses in a solution of the polymer in a Organic solvent to form the paint mixture. Polymer it has hydrophilic groups, so it acts to stabilize the water-in-oil emulsion of the base mixture in the solution of polymer. It also has functional groups that will react with the crosslinker A crosslinker that is not modified is used hydrophilically and that is soluble in the organic solvent. Fair before using it, the crosslinker is added to this dispersion and dissolve in the solvent and then this mixture is finally dispersed in water The polymer also stabilizes this oil dispersion in Water. This method allows the use of crosslinkers without groups hydrophilic, while allowing the formation of compositions with a significantly volatile organic content lower than those made following routes conventional.

According to the present invention a solvent-based pigmented paint mixture that can become a water-based coating composition, which understands;

i) a water-based pigment dispersion, which comprises pigment dispersed in water in the presence of a pigment dispersant, the pigment dispersion itself being water base dispersed with

ii) a solution in an organic solvent of polymer with functional groups and hydrophilic groups.

The present invention also provides a solvent-based activated paint mixture comprising the solvent-based paint mixture and a crosslinker that is dissolves in the organic solvent.

The present invention also provides a water-based coating composition comprising a dispersion in an aqueous medium of the activated paint mixture a solvent base.

According to the present invention also provides a process to produce a mixture of paint based on solvent that can become a coating composition water-based pigmented comprising a polymer with groups functional and hydrophilic groups and a crosslinker for the polymer, which comprises the stages of:

i) form a solution of the polymer in a organic solvent,

ii) disperse a dispersion of pigment based of water in the polymer solution.

The present invention also provides a process to produce an activated paint mixture based on solvent that can become a coating composition aqueous, comprising the step of adding to the paint mixture a solvent base a crosslinker that is soluble in the solvent organic and form a solution of the crosslinker in the solvent.

The present invention also provides a process to produce an aqueous coating composition that comprises the additional step of emulsifying the paint mixture activated based on solvent in an aqueous medium.

Organic solvents include any non-aqueous solvent that can be used to dissolve the polymer and It has little or no water solubility. It can be a aliphatic or aromatic hydrocarbon such as Solvesso 100®, toluene or xylene, an alcohol such as butanol or isopropanol, an ester such as butyl acetate or ethyl acetate, a ketone such as acetone, methyl isobutyl ketone or methyl ethyl ketone, an ether, a ether-alcohol or an ether-ester or a mixture of any of them.

The polymer can be any polymer with functional groups and hydrophilic groups, which can act to stabilize the dispersion of the aqueous base mixture in the solution of polymer and that can stabilize the paint mixing emulsion activated in the aqueous phase.

Functional groups are groups that can react with a crosslinker to crosslink the polymer in the layer of definitive coating. For example, functional groups they can be amine groups, hydroxyl groups, acetoacetate groups, silane groups, carboxylic acid groups or epoxy groups, preferably hydroxyl groups or epoxy groups and most preferably hydroxyl groups. Examples of hydrophilic groups Suitable are carboxylic acid groups and amine groups. When the hydrophilic groups are carboxylic acid groups, the polymer has preferably an acid number of 20 to 250. When the groups hydrophilic are amine groups, the polymer preferably has a amine number from 20 to 250. Preferably, the acid groups or polymer amine are at least partially neutralized and more preferably, they are completely neutralized. For example, the acid groups can be neutralized using a suitable base such as ammonia or an amine such as dimethylethanolamine, and the amine groups they can be neutralized using an acid such as lactic acid or acid acetic. When hydrophilic groups are amine groups or groups carboxylic acid, these can also act as groups functional.

The polymer can be an addition polymer vinyl, a polyester, a polyurethane, a mixed polyester polyurethane or an epoxy polymer, preferably a vinyl addition polymer, a polyester, a polyurethane or a mixed polyurethane polyester and more preferably a vinyl addition polymer.

Preferred polymers have a molecular weight numerical medium, measured by gel permeation chromatography, of 700 to 10,000, more preferably 1,000 to 4,000. Preferably, when the polymer has hydroxyl groups it has an index of hydroxy of 5 to 500, more preferably 50 to 250.

Preferred polymers have an index of acidity (AI) of up to 50. The acid number is the mass of hydroxide of potassium in milligrams necessary to neutralize acid groups in 1 gram of solid resin.

Suitable polyesters are derived from an acid polybasic and a polyhydroxy compound and normally has hydroxyl function

Polybasic acids are compounds with two or more carboxylic acid groups. These polybasic acids are fine known in the art of polyester. Acid Examples Suitable polybasic are alkane acids C 1-6 -dioics such as acid succinic, glutaric acid, adipic acid or hexanedioic acid, cycloaliphatic acids such as hexahydrophthalic acid, acids unsaturated alkanedioids such as fumaric or maleic acids, dimeric acids, and aromatic acids such as phthalic acid, isophthalic acid and trimellitic acid. Instead of free acids ester forming derivatives of said acids can be used. Ester-forming derivatives include anhydrides and alkyls lower, for example methyl or ethyl esters. Can be used mixtures of two or more acids or their derivatives ester.

Polyhydroxy compounds are compounds with two or more hydroxyl groups and are well known in the art of polyester. Examples of suitable polyhydroxy compounds are diols such as ethylene glycol, propylene glycol, 1-3-propanediol, butylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, triols such as trimethylolpropane and glycerol, tetroles such as pentaerythritol and higher polyols such as sorbitol. Mixtures of two or more of these polyols can be used.

Polyurethanes or mixtures of polyester polyurethane can be formed similar to polyesters, although using a di- o polyisocyanate instead of some or all of the polybasic acids They generally have hydroxyl function. Suitable diisocyanates are tetramethylxylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and toluene diisocyanate. Suitable polyisocyanates include the isocyanurate, allophanate and uretdione diisocyanate trimers such as those described above, as well as the products of reaction of these diisocyanates with polyols. The polyols are compounds with two or more hydroxyl groups. Suitable polyols they include trimethylolpropane, glycerol and pentaerythritol. Many of said polyisocyanates are commercially available, for example under the trademark Desmodur of Bayer or the trademark Rhodia tolonate.

Polyester, polyurethane or polyester polyurethane can be formed by means conventional. Generally, polyester components are melt together or dissolve in a suitable solvent, such as xylene. The melt or solution is then heated to separate the water produced in the reaction between the acid and hydroxyl groups. When the components melt together, the water can separate using a fractionation column at temperatures between 150 and 250 ° C When the components dissolve in a solvent, the water can be conveniently separated by azeotropic distillation using a Dean and Stark apparatus at the reflux temperature of the solvent. A combination of these methods can be used, melting initially the components together and separating the water with a fractionation column and then adding solvent and separating more water using a Dean and Stark device. If there is that include a polyisocyanate to produce a polyester polyurethane, this is usually added after the reaction of the other components and at a temperature lower, such as between 50 and 100 ° C, since the groups Isocyanates are much more reactive than acid or ester groups.

Acrylic addition polymers are derived from polymerizable ethylenically unsaturated monomers such as vinyl or acrylic monomers, and comprise functional units, hydrophilic units and structural units. Whenever it is done reference herein to the expression acrylic monomer reference is made to esters of acrylic or methacrylic acid. He term (meth) acrylate refers to both acrylate and methacrylate and the expression (meth) acrylic acid refers also to acrylic or methacrylic acid.

Functional units are derived from monomers vinyl or acrylics that have functional groups in them. By For example, glycidyl methacrylate can be used to produce a polymer with groups with epoxy function and methacrylate of aminoethyl to produce a polymer with groups with amine function. Polymers with hydroxyl functional groups can be made using vinyl or acrylic monomers with hydroxyl function. An example of A vinyl monomer with hydroxyl function is vinyl alcohol. Examples of acrylic monomers with hydroxyl function are (meth) hydroxyethyl acrylate, (meth) acrylate hydroxybutyl and hydroxypropyl (meth) acrylate.

Other examples of monomers with hydroxyl function suitable are the reaction products of (meth) acrylate of glycidyl with monocarboxylic acids, such as versatic acid and the reaction product of (meth) acrylic acid with monoepoxy compounds such as Cardura E® (the glycidyl ester of versatic acid; Shell)

Hydrophilic units are derived from monomers with hydrophilic groups. Examples of monomers with groups Hydrophilic are monomers with acid function, such as acid acrylic and methacrylic acid and amine function monomers such as dimethylaminoethyl acrylate.

The structural units are derived from monomers that have no functional group that reacts with the crosslinker, or any hydrophilic group. Examples of monomers of those that can be derived structural units are monomers non-functional vinyl and alkyl acid esters (meth) acrylic.

Examples of non-functional vinyl monomers Suitable are styrene, tert-butyl styrene and alpha methyl styrene, preferably alpha methyl styrene. Examples of Suitable alkyl esters of (meth) acrylic acid are C 1-12 alkyl esters such as (meth) methyl acrylate, (meth) ethyl acrylate, (meth) n-butyl acrylate, (meth) t-butyl acrylate, (meth) n-propyl acrylate and (meth) isobornyl acrylate.

Weight regulators can also be added molecular such as mercapto compounds, for example n-octyl mercaptan, to control the weight molecular.

Preferred Acrylic Addition Polymers they have a theoretical glass transition temperature (Fox Tg) of -30 at 80 ° C, more preferably -10 to 50 ° C.

Many suitable acrylic addition polymers They are commercially available. They can also be produced by conventional means. The acrylic addition polymer can be produced by contacting a mixture of the monomers suitable with a polymerization initiator at a temperature at that polymerization takes place. For example, the mixture of monomers can be fed slowly to a solution of the initiator maintained at the polymerization temperature or it can feed the initiator to a solvent at the temperature of polymerization simultaneously with the monomer mixture.

Suitable initiators are such azo initiators as azodiisobutyronitrile and 2,2'-azobis (2-methylbutyronitrile) or peroxy initiators such as benzoyl peroxide.

The pigment is dispersed in water using a suitable pigment dispersant. A pigment dispersant suitable is Dispex GA40®.

The term pigment includes fillers and diluents, as well as conventional pigments. Pigments are materials in particles that impart color or opacity to the final coat of paint. Diluents and fillers are normally inorganic materials which can be used to reduce the cost of a formulation or to Modify its properties. Particularly, the charges and Diluents can be used in primers to improve their ability to hide small surface imperfections and also to facilitate sanding to achieve a smoother surface for Subsequent application of finishing paint. It has been determined that the process of the present invention is particularly beneficial in the production of primer paints because these contain a relatively high level of pigment, so that the reduction of VOC achieved through this process results especially remarkable.

Crosslinkers are compounds that react with at least two functional groups in the polymer to crosslink the composition. When the functional groups are acidic groups carboxylic, an example of a suitable crosslinker is a carbodiimide. When the functional groups are amine groups, examples of Suitable crosslinkers are polyepoxides and polyisocyanates. When functional groups are epoxy groups, examples of crosslinkers Suitable are polyamines. When the polymer functional groups they are hydroxyl groups, examples of suitable crosslinkers are phenol formaldehydes, melamine formaldehydes and polyisocyanates.

Polyisocyanates are crosslinkers preferred. Polyisocyanates are compounds with two or more groups isocyanate per molecule and are well known in the art of coatings Isocyanate groups can be blocked, although Prefer free isocyanate groups.

Suitable diisocyanates are diisocyanate of tetramethylxylene, hexamethylene diisocyanate, diisocyanate toluene and isophorone diisocyanate. Preferably the polyisocyanate has an isocyanate functionality of 2.5 or more isocyanate groups per molecule. Suitable polyisocyanates of this type include isocyanurate, allophanate and uretdione trimers of diisocyanates such as those described above, as well as the reaction products of said diisocyanates with polyols. The Polyols are compounds with three or more hydroxyl groups. Polyols Suitable include trimethylol propane, glycerol and pentaerythritol. Many of these polyisocyanates are commercially available, for example under the Bayer brand Desmodur or the brand Tolonate commercial from Rhodia.

The aqueous medium comprises at least 50% by weight of water, preferably at least 90% and more preferably, practically everything, for example 99.5% water. The other components of the aqueous medium may be miscible organic solvents in Water.

The compositions may also contain catalysts for the reaction between the functional groups of the polymer and crosslinker. For example, catalysts suitable for the isocyanate-hydroxyl reaction include tin catalysts such as dibutyltin dilaurate and amine type catalysts such as triethylamine. The compositions may also contain other paint additives conventional such as pigments, fillers, UV absorbers and fluidifying agents

The polymer solution can be formed by preparing the polymer in organic solvent or simply by stirring the polymer with organic solvent.

The pigment base mixture can be made mixing the pigments, fillers and diluents and the dispersant of pigments, optionally with a little water in a high mixer shear like a ball mill or a rotary disperser of high speed to thoroughly separate the pigment particles and coat them with dispersant.

The crosslinker can dissolve in the solvent organic mixing, for example stirring. The polymer mixture a solvent base, crosslinker and water based base mixture dispersed can be dispersed in the aqueous medium by agitation.

The coating composition of the invention can be applied to the surface of a substrate and leaving or causing it to dry and cure. According to the present invention, provides a process for coating a substrate, which comprises the steps of applying a coating of a coating composition according to the present invention to a substrate surface, causing or allowing after the layer to cure.

The coating composition can be applied by conventional means such as brush, roller or spraying, preferably by spraying. The substrate it can be, for example, metal, plastic, wood or glass. The compositions are especially useful in the finishing of motor vehicles when they can be used as finishing paint, to Although they are especially useful as a primer.

The applied layer can be allowed to cure ambient temperature in the case where the polymer and the crosslinker react together at room temperature. Alternatively, the layer can be cooked at elevated temperatures, for example 50-120 ° C to accelerate curing. Drying and Curing normally takes between 5 minutes and 24 hours depending on the environmental conditions and the particular components used It conveniently takes between about 15 minutes and around 5 hours

According to the present invention, it is provided also a coated article that can be obtained by process.

The invention will be illustrated below by The following examples in which all parts are by weight.

Examples 1. Water based pigment base mix

A dispersant was mixed together (Dispex GA40®, 2,991 parts), an antifoaming agent (Synperionic DF210®, 0.300 parts) and water (11.762 parts) and were introduced in a high speed disperser The disperser was started and constantly added zinc oxide (2,054 parts), zinc phosphate (14,266), talc (24,414 parts), calcium carbonate (16,270 parts), titanium dioxide (Tipure R960-09®, 21,563 parts) and black organic dispersion (Sandosperse®, 0.488 parts) to avoid lump formation Water (5,882) was added with the pigment to Maintain a fluid mixture. High speed agitation is continued for 45 to 60 minutes. Mixing continued for 5 more minutes

2. Acrylic polymer with hydroxyl function

A mixture of alpha methyl was slowly added styrene (6.65 parts), tertiary butyl acrylate (19.96 parts), hydroxybutyl acrylate (19.16 parts), acrylate butyl (11.99 parts), acrylic acid (2.14 parts), azidiisobutyronitrile (Vazo 67®, 2.57 parts), n-octyl mercaptan (2.33 parts) and butyl acetate (7.18 parts) to a mixture of butyl acetate (21.14 parts) and alpha methyl styrene (6.65 parts) for 180 minutes at a temperature of 135 ° C. The mixture was maintained at 135 ° C for 15 minutes and then more initiator was added (Triganox 21S®, 0.115 parts). The mixture was stirred for an additional 60 minutes, after which it was added more initiator (Triganox 21S®, 0.115 parts). The mixture is held at 135 ° C for 60 minutes before allowing to cool.

The hydroxyl functional polymer had an index of acidity of 28.

3. Pigmented paint mix

A mixture of dimethylaminoethanol (0.57 was added parts) and water (5.16 parts) to the polymer solution produced in the previous point 2 (15.77 parts). This mixture was added to the pigment base mixture prepared in point 1 above (73.87 parts) with stirring, followed by butyl acetate (4.57 parts) and dibutyltin dilaurate catalyst (0.06 parts).

4. Primer compositions

Three primer compositions were made according to the invention with three polyisocyanate hardeners different. The components listed in Table 1 below then.

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Composition Hardener of polyisocyanate Paint mix pigmented Hardener Water one Tolonate HDT90 fifty 3.05 5 2 Desmodur Z4470 fifty 5.15 7.1 3 Cythane 3174 fifty 5.8 7

5. Comparative trials

Two primer compositions were made, the Composition 4 according to the invention and comparative composition 5 using hydrophilically modified polyisocyanates that were added to the aqueous composition after mixing the base mixture and the water. These compositions used the pigmented paint mixture of item 3 previous (300 parts). For composition 4, it was added to the mixture of paint a hydrophilically unmodified polyisocyanate, Cythane 3174® (34.8 parts) with stirring and then water (43.8 parts) with stirring to obtain the final paint composition 4. For comparative composition 5 water (43.8 parts) was added to the paint mixture and then stirring was added a Desmodur VPLS 2032® hydrophilically modified polyisocyanate (39.6 parts).

These primer compositions were applied by spraying steel panels to give them a thickness of 80 micron dry film in three layers. They were allowed to dry and cure the panels for 24 hours at room temperature (around of 20 ° C).

The primer coatings were sanded dried with P300 sandpaper and a mechanical sander to achieve a smooth finish, after which they finished with paint finishing commercial two-component black polyurethane. It was allowed to dry room temperature for 1 hour and then heated for 30 minutes at 60 ° C.

The panels were tested with primer and with finish to determine Konig hardness and resistance to water absorption. Water absorption resistance is measured according to the SMMT (Test of the vehicle manufacturers society a motor, in its acronym in English) number 57. The results were the following:

Appearance Water absorption SMMT Accession Primer 4 Lisa and sparkly 8M 33 Comparative Primer 5 Bright with holes 8MD one

The result of the resistance test to water absorption indicates the blistering of the paint past 3 days. M means medium blisters and MD means very blisters dense The blister size of 8 is on a scale of 1 to 10, in where 1 is 10 mm and 10 is microscopic. The adhesion indicates the percentage of coating that remains intact after applying tape Adhesive to the test finish layer and remove it.

This absorption resistance test shows clearly the benefits of the process and the composition according to the invention that avoids the need for polyisocyanates hydrophilically modified, while providing a VOC much lower than that achieved using solvent based mixtures known in conjunction with unmodified polyisocyanates hydrophilically.

6. Finishing composition

A white finish paint was prepared according to the invention as follows

White base mixture of water-based pigments

A dispersant was mixed (Dispex GA40®, 26.5 parts), an antifoaming agent (Synperionic DF210®, 9 parts), polypropylene glycol (100.0 parts) and water (150.0 parts) and it introduced in a high speed disperser. The disperser is launched and titanium dioxide was constantly added (Tipure R960-09®, 1393.0 parts) to prevent the formation of lumps Water (183.0 parts) was added with the pigment to maintain a fluid mixture Stirring was continued at high speed for 45 to 60 minutes Mixing continued for another 5 minutes.

White Pigmented Paint Mix

A 10% aqueous solution of dimethylaminoethanol (7 parts) to the polymer solution produced in the previous point 2 (200.00 parts). This mixture was added to white pigment prepared previously (190.0 parts) with stirring, followed by butyl acetate (820 parts), and catalyst of dibutyltin dilaurate (0.25 parts).

White finish composition

A white finish layer was made combining the paint mixture prepared as indicated above (164 parts), a polyisocyanate (Cythane 3174®, 46.0 parts), a 10% aqueous solution of dimethylaminoethanol (14.0 parts) and water (200.0 parts).

Application and test

The paint was allowed to set for 30 minutes after mixing to achieve a low composition adequate viscosity for spraying. The composition on a steel panel with primer layer with a dry film thickness of 40 micrometers. It was allowed to dry for 1 hour at room temperature (around 20 ° C) and then heated in an oven for 30 minutes at 60 ° C.

The resulting topcoat was smooth, shiny and free of defects with a brightness of 70 at an angle of 20 degrees and with a Koenig hardness of 53.

Claims (22)

1. A solvent-based paint mixture pigmented that can become a coating composition Water based, comprising: i) a water-based pigment dispersion that comprises pigment dispersed in water in the presence of a dispersant of pigment, the aqueous pigment dispersion itself being in dispersion in ii) a solution in an organic solvent of polymer with functional groups and hydrophilic groups. 2. A paint mixture according to claim 1, in which the functional groups are hydroxyl groups. 3. A paint mixture according to claim 2, in which the polymer has a hydroxyl number of 5 to 500 4. A paint mixture according to claim 3, in which the polymer has a hydroxyl number of 50 to 250 5. A mixture of paint according to any of the preceding claims, wherein the hydrophilic groups are carboxylic acid groups or amine groups. 6. A paint mixture according to claim 5, in which the hydrophilic groups are carboxylic acid groups and The polymer has an acid number of 20 to 250. 7. A paint mixture according to claim 5, in which the hydrophilic groups are amine groups and the polymer It has an amine index of 20 to 250. 8. A mixture of paint according to any of the preceding claims, wherein the polymer is a polymer of vinyl addition, a polyester, a polyurethane, a mixed polyester polyurethane or an epoxy polymer. 9. A paint mixture according to claim 8, wherein the polymer is a vinyl addition polymer, a polyester, a polyurethane or a polyester-polyurethane mixed. 10. A paint mixture according to claim 9, wherein the polymer is a vinyl addition polymer. 11. A paint mixture according to claim 10, in which the polymer has a glass transition temperature theoretical (Fox Tg) from -30 to 80ºC. 12. A paint mixture according to claim 11, in which the polymer has a glass transition temperature theoretical (Fox Tg) from -10 to 50ºC. 13. A mixture of paint according to any of the preceding claims, wherein the polymer has a number average molecular weight measured by permeation chromatography gel 700 to 10,000. 14. A paint mixture according to claim 13, in which the polymer has a number average molecular weight of 1,000 to 4,000. 15. A mixture of paint according to any one of the preceding claims, wherein the polymer has a acid number of up to 50. 16. A mixture of activated paint based on solvent comprising the solvent based paint mixture according to any one of claims 1 to 14 and a crosslinker which dissolves in the organic solvent. 17. A solvent activated paint mixture according to claim 16, wherein the crosslinker is a phenol formaldehyde, melamine formaldehyde or polyisocyanate. 18. A mixture of activated paint based on solvent according to claim 17, wherein the crosslinker is a polyisocyanate. 19. A process to produce a mixture of solvent-based paint that can become a pigmented water based coating composition comprising a polymer with hydrophilic groups and functional groups and a crosslinker for the polymer, comprising the steps of: i) form a solution of the polymer in a organic solvent, ii) disperse a dispersion of pigment based of water in the polymer solution. 20. A process to produce a mixture of activated solvent-based paint that can become a aqueous coating composition comprising the process of claim 19 and the additional step of adding to the mixture of solvent-based paint a crosslinker that is soluble in the organic solvent and form a solution of the crosslinker in the solvent 21. A process to produce a composition of aqueous coating, comprising the process of claim 20 and the additional step of emulsifying the activated paint mixture solvent based in an aqueous medium. 22. A process for coating a substrate, which it comprises the steps of applying a layer of a composition of water-based coating according to claim 21 to a substrate surface, causing or allowing after the layer cure.